This invention relates to silver halide color photographic photosensitive materials, and more precisely to silver halide color photographic photosensitive materials of which the stability of the photographic sensitivity during manufacture and storage and of the colored image after processing are excellent.
The dye images of silver halide color photographic materials may be maintained under conditions in which they are exposed to light or kept in the dark for long periods of time and it is known that the image fades considerably whatever the conditions, depending on the wavelength and quantity of the light, or conditions such as the heat, humidity and oxygen, etc., to which it is exposed. In general, fading on exposure to light for long periods is known as light fading and fading which occurs in the dark is known as dark fading. In cases where a processed color photographic material is to be stored for a long period of time as a recording medium, it is desirable that the balance between the extent of fading of the yellow, magenta and cyan dye images should be preserved while suppressing as far as possible the extent of light fading and dark fading, while raising the light fastness and dark fastness of the colored image. However, the extent of light fading and dark fading of each of the yellow, magenta and cyan dye images differ and, on storing for long periods of time, the overall tricolor balance is destroyed. This is disadvantageous in that the image quality deteriorates both in terms of color reproduction and gradation.
The extent of light fading and dark fading differs depending on the couplers which have been used and various other factors but, with the dyes which have often been used in color photographic photosensitive materials in the past, the cyan dye image has been most liable to dark fading, followed by the yellow dye image and the magenta dye image. It is well known in the art that the extent of the dark fading of the cyan dye image is markedly greater than that of the other dye images.
Thus, the dark fading of the cyan dye image must be suppressed as much as possible if a good color balance is to be maintained over long periods of time when tricolor yellow, magenta and cyan fading occurs. Consequently, various attempts have been made in the past to provide improvements with respect to light fading and dark fading. These attempts can be broadly divided into two types. The first type involves the development of new couplers which form dye images which are less prone to fading while the second type has involved the development of new additives designed to prevent the occurrence of fading.
A great many phenolic type cyan couplers are known for the formation of cyan dyes. For example, the 2-(.alpha.-2,4-di-tert-amylphenoxybutanamido)-4,6-dichloro-5-methylphenol disclosed in U.S. Pat. No. 2,801,171, forms a colored dye which has good resistance to light, but it is also known to have poor heat resistance.
Moreover, couplers in which the 3- and 5-positions of the phenol are substituted with alkyl groups which have at least 2 carbon atoms are disclosed, for example, in Japanese Patent Publication No. 11572/74 and Japanese Patent Application (OPI) Nos. 209735/85 and 205447/85 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"). The dark fastness of the cyan images formed with these couplers is improved to a certain extent, but is still imperfect. Moreover, it is known that the light fading characteristics are worse than those obtained with the aforementioned cyan couplers.
Furthermore, 2,5-diacylaminophenol based cyan couplers, in which the 2- and 5- positions of the phenol are substituted with acylamino groups, are disclosed, for example, in U.S. Pat. Nos. 2,369,929, 2,772,162 and 2,895,826 and Japanese Patent Application (OPI) Nos. 112038/75, 109630/78 and 163537/80. The dark fastness of the cyan images formed with these 2,5-diacylaminophenol based couplers is very good, but the light fastness of the cyan images which are formed is worse than that obtained with the two types of cyan couplers referred to above. Furthermore, when these materials are used in photosensitive materials for obtaining prints, there is a further disadvantage in that the hue is biased slightly to the short wavelength side. This type of coupler has been used in the form of mixtures with cyan couplers of the two types mentioned above in order to overcome this problem, but this is known to have an adverse effect on the dark fastness.
In general, the 1-hydroxy-2-naphthamide type cyan couplers have inadequate light fastness.
Furthermore, the 1-hydroxy-2-acylaminocarbostyril cyan couplers disclosed in Japanese Patent Application (OPI) No. 104333/81 are fast to both light and heat. However, the spectral absorption characteristics of the colored images formed with these couplers are not preferred for color reproduction in color photography, and it has been discovered that these couplers also give rise to problems such as the formation of pink stains on irradiation with light, etc.
The cyan polymer couplers disclosed in U.S. Pat. No. 3,767,412 and Japanese Patent Application (OPI) Nos. 65844/84 and 39044/86, for example, have excellent dark fastness under low humidity conditions. However, they have been found to have inadequate dark fastness under conditions of high humidity.
Furthermore, methods in which hydrophobic substances such as oil soluble couplers, etc., are dissolved in organic solvents which are miscible with water and then mixed with a loadable polymer latex, so that the hydrophobic substances are loaded onto the polymer have been developed, are disclosed in U.S. Pat. No. 4,203,716, for example. However, when methods of this type involving the use of a loadable polymer latex are employed, problems arise with regard to a deterioration of the light fastness of the cyan image, particularly, when compared to cases in which water-immiscible high boiling point organic solvents are employed. Moreover, a large quantity of polymer must be used in order to carry a sufficient quantity of coupler and to obtain a satisfactory maximum color density.
This has been found to be disadvantageous both in terms of the cost of the photosensitive materials in which these materials are used and in view of the increase in film thickness. Photosensitive materials which contain emulsified dispersions of couplers in which homopolymers of hydrophobic monomers of a specified structure, or copolymers with hydrophilic monomers which have a specified structure, which are soluble in organic solvents are used in place of the high boiling point organic solvents with which the film properties, recoloring failure, light fading and storage properties before processing are improved, are disclosed in Japanese Patent Publication No. 30494/73. However, it has been found that when a homopolymer of a hydrophobic monomer, such as those referred to above, is used to replace a high boiling point organic solvent, the color forming ability is reduced, especially in developers which do not contain benzyl alcohol, and that the stability of the emulsified dispersion is poor during storage. On the other hand, copolymers of the aforementioned hydrophobic monomers with hydrophilic monomers, such as acrylic acid, improve the stability of the emulsified dispersion and also improve the color forming properties. However, the effect is totally inadequate. Moreover, it has been found that the dark fastness deteriorates, especially under conditions of high humidity, when the proportion of hydrophilic monomer in the copolymer is increased in order to improve the color forming properties.
Furthermore, when the method of Japanese Patent Publication No. 30494/73 is applied, especially in the case of a cyan coupler, there is a serious problem in that the light fastness is markedly worse than the case wherein a cyan coupler is emulsified and dispersed in a conventional high boiling point organic solvent.
Thus, in the past, all of the couplers of which dark fastness has been improved through modification of the coupler structure, have proven to be inadequate with respect to hue, color forming properties and staining. More particularly, these methods have proved to be inadequate with respect to light fastness. Therefore, a novel technique for overcoming all of these problems simultaneously is required.
Benzyl alcohol is widely used for improving color forming properties and reducing processing times in the color development of silver halide color photosensitive materials in which conventional oil protected type couplers have been used.
However, benzyl alcohol has low water solubility and solvents such as diethylene glycol, triethylene glycol or alkanolamines have therefore been required to facilitate the dissolution of the benzyl alcohol. These compounds, including benzyl alcohol, have a high BOD (biological oxygen demand) and COD (chemical oxygen demand) values, which indicate the extent of environmental pollution. Therefore, it is desirable from the point of view of environmental protection that these compounds not be used.
Moreover, when benzyl alcohol is used, there is still a disadvantage in that time is required to form a solution, even when the above-mentioned solvents are used.
Furthermore, if the benzyl alcohol is carried over into the bleach bath or bleach-fix bath, the leuco form of the cyan dye is readily formed, resulting in a lowering of the color density. Moreover, the wash-out rate of the developer components is retarded, and there are cases where this has an adverse effect on the image storing ability of the processed photosensitive material. Hence, it is also desirable that benzyl alcohol not be used from these points of view.
Accordingly, the development of couplers, and emulsified dispersions thereof, which provide improved image storage properties, and which have good color forming properties without the use of benzyl alcohol, is desirable.
On the other hand, it has been discovered that couplers or emulsified dispersions which have excellent color image fastness, such as those described earlier, often act on a silver halide emulsion in such a way as to affect the photographic speed. That is to say, it has been found that there is a lowering of color sensitized speed when the phenol based cyan couplers described earlier are used, and a similar desensitization is observed when certain types of magenta coupler or yellow coupler are used. It is desirable that any technique used for improving the fastness of the color image should not have any such action, and the development of emulsion technology in which such effects are unlikely to arise has been predicted.
Hence, the first aim of the invention is to provide silver halide color photographic photosensitive materials in which the light fastness and dark fastness are improved, and more precisely, with which it is possible to form color images which have excellent storage properties, even under conditions of high temperature and high humidity.
The second aim of the invention is to provide silver halide color photographic photosensitive materials which have a good balance between yellow, magenta and cyan color fading, and with which color reproduction does not deteriorate even on long term storage.
The third aim of the invention is to provide silver halide color photographic photosensitive materials with which a dye image having good color image storage properties can be formed without adverse effect on the photographic properties, and more precisely, without reducing the photographic sensitivity during the manufacture or storage of the photosensitive material.
The fourth aim of the invention is to provide silver halide color photographic photosensitive materials which have adequate color forming properties even when processed in color developers which are essentially benzyl alcohol free and which have excellent color image storage properties, consisting of coupler emulsified dispersions which have excellent stability.
The fifth aim of the invention is to provide silver halide color photosensitive materials in which, in terms of the fastness of the cyan dye image, the dark fastness is improved without degrading the light fastness.